Pantograph



Sept. 29, 1931. J. A. CLARKE, JR

PANTOGRAPH Filed Dec. 6, 1927 -uri 3 INVENTOR Job 6': C/a/n aL/n ATTORNEY i UNITED STATES Patented Sept; 29, 1931 v PAT JOHN AVCLARKE, an, OFPI'ITSBURGH, PENNSYLVANIA, 'Ass I'e oR'ro WESTINGHOUSE ELECTRIC & M NUFACTURING- COMPANIVAI oosPo'RA'r oN'or PENNSYLVANIA PANTOGRAIH Application filed December 6, 1927. Serial No. 238,193.

My invention relates to current collectors and more particularlyto mechanisms for actuating pantograph trolleys suitable for e'lecg trically driven railway vehicles.

mon practice to provide an'operating mecha- In the devices of thefprior art, it iscomnism comprising a spring system for raising the pantograph trolley and for maintaining the proper contact pressure with the trolley conductor, a fluid-pressure cylinder for IGf tracting the pantograph toits'lowermost position and an automatically operable latch for locking it in its retracted position.

Another type of pantograph-operating mechanisml'that hasbeen empl'oyedin the devices of the priorart comprises a pantograph frame biased in the upward directio'nz'by means of springs and provided with fluid-pressure cylinders for stretching the springs to increasetheir tension and com plete the upward movement of the pantograph frame. This'type of structure is objectionable in that the pantograph frame is caused to accelerate during itsupward movement whereby the contact member ap preaches the trolley conductor at an excessive speed. i

' A further difliculty encountered withthe devices of the prior artarises from the fact that therpantograph frame is accelerated during its downward movement and may strike the supporting frame oricar roof at damaging blow unless cushioning means are provided. 1

' It is an'objectof my invention to provide a pantograph-trolley-opcrating mechanism that will move thepantographframe at a substantially uniform speed and therebyengage the contact member with the. trolley conductor at a uniform speed"'and. with a steady pressure. o Another objectofmy invention isto provide meansfforfretracting the trolley" contact member-from the trolley conductor at a relatively high speed to quickly extinguish a'possible arc. v:

A further object-10f my invention is to provide means for lowering the pantograph its lowermost position to provide buffing means vforcushioning the trolleyframe and for; bringing it to its lo'westposition without shock. o: :tf, l I '7 In the accompanying drawings; a Figure 1 is a planview of a pantogra'phtrolley structure embodying the principles of my invention .a portion of' the jcontact memberfbeing brol: i i the operating mechanism; I I I e i Fig. 2- is a'view, in side elevation, of the trolley structure shown, witha pantograph frame in a partially extended positlm en away to jmore clearly how t ENT} omen "Referring. to the drawingsflthe; pantog graph-trolley; structure therein illustrated comprises a supportinglframe 1 that 'ma'y be mounted'on; the roof of fa railway vehicle by means of'a plurality'of insulators 2 that are disposed in. pairs under its side'members. 7

The supporting frame is composed of parallel longitudinally disposed members preferably in the. form, of angle irons, that are mounted 'on"the"tops ofthe insulators 2. The longitudinally disposed-members 3 are connected by; means of transverse crossmembers 4 that are disposed to support the operating mechanism for raising or lowering the pantjograph. I o I The longitudinal" frame members 8 vfurther serve as supports for pantograph shafts 5 that are journalled in spaced parallel relation transversely of the supporting frame. The pantograph shafts 5 serve to support the pantograph frame 6 in a manner well known in the art. Each ofthe pantograph shafts 5 is provided with two cams 9'that are secured near theirendsto rotate with them. The cams 9 are provided vwith lugs 10 to whicharesecured the endsof tubes 11 that o constitute the'lower members ofthe p antograph frame 6... The lower members ll'are connected to upper members 12 by means of pivotal joints 13 The upper members v12 of the pantograph' frame 6 are connected by means of 'joint members 15 i that serve' to strengthen the structure and also to pivotally support a pa-ir of contact members. 16. p

, In'order to provide the necessary force for raising the pan tograph, relatively heavyv springs 18 are disposed atthe Sides of the structure in longitudinal alinement with the cams 9. The ends of the springs 18 are operatively connected to the cams 9 by means of chains 19 that are disposed to wind upon the curvedsurfaces of the cams 9 in such manner that the contact members 16 are caused. to exert a substantially constant. pressure against a trolley conductor 20 at any position within the limits of its vertical operating. range;

interconnected by means of equalizer bars 24 to provide a parallel-motion devicethat is disposed to limit the movement of'the contact members 16 to a substantially verti- V pantographshafts -5'.. Ina-order to-operatively connect the shaft 33 to the. panto graphshatt. 53-3 crank arm 34 is securely fastened? to the shaft 33- and is pivotally connected topne end ofia link 35. The other end of the link. 35-. is provided with a. slot 36 for engaging a. 3.7 that is mounted in the end of a crank. arm 38* The crank arm 3'8is securelymounted on. onevof the pantofi graph shaftsfi in longitudinal'alinement with the crank arm on. the shafl1'33uv Refierring to lli'g; the springs 31 exert a force upon. the crank arms '32. thattends to rotate the shaft. 33 clockwise. It will be seen that the link 35 will. be. forced to the right by the crank arm 34. and when the lost motion permitted by the slot 36 is. takenup,

' the Link. willv engage the pin. 37 in the crank arm 38* to bias the antograph shaft 5* in the clockwise direction and thereby retract the pantograph frame 6.. The springs 31 are so adjusted that, when the pantograph frame. 6 is inthe fully retracted position, they exert a force that is sulhcient to overcome the tendency of the springs 18 to. raise the pantograph frame 6..

- With: a View to: providing. means for controlling the position of the pantograph frame 6, a. crank. arm: 41 is securely attached toil 6 shaft 33- at substantially the transverse center of the 'pantograph structure- The end of the crank arm 41 is engaged. by a piston rod .42 that extends from a fluid pressure cylinder 43. When it is desired to raise. the

pant'ograph to its operating position, fluid is: admitted, at a predetermined relatively slow rate,.to the cylinder 43 through a pipe that is connected to a source of fluid pres- The ends of the shafts-15 are providedw i-th crank -arms 2'3 that are:

sure and controlled by means of the usual valve mechanism (not shown).

The fluid pressure within the cylinder 43 causes the piston rod 42 to be moved to the left, as viewed in the drawings, and thereby rotates the shaft 33 counterclockwise by means of the crank arm .41. When the shaft 33 is so rotated, the link 35 is moved to the left by means of the crank arm 34, thereby permitting the crank 38 on: the shaft 5 tom'ove to the left and the pantograph frame 6 to be extended under the influence of: raising springs 18.

After the pantograph frame 6 has been extendedsufiicientlyto engage the contactmembers 16 with the trolley conductor. 20, the pantograph frame 6' comes to rest. ;As additional fluid is admitted to the cylinder 43, the link 35- is moved further to the left,

thereby removing all pressure from the pin 37,-ot' the crank arm 38. When the piston rod 42 has been actuated to the limit of its movement to the left, the link 35 will be in such position that the pin 37will' not engage either end of the slot 36 Under these conditions,ft"hepantograph frame 6 is biased in the upward direction by means of the springs 18- only, and the frame isfree to move vertically to compensate for variations in the height of the trolley conductor 20 by virtue of the lost-motion connection between the link 35' and the crank arm 38,

When the pantograph is'in its raisedposition, it. is disposed to exert a substantially constant upward; force against the trolley conductor 20, as .hereinhefore. explained, and, inasmuch as the lowering springs 31 and the mechanism connected thereto, are entirely disengaged from the pantograph frame 6,,the: remaining mechanism, comprising the parallel-motion device and the pan.- tograph frame 6, is of relatively light weight and disposed to sensitively and quickly follow irregularities in the trolley conductor 20]. i i

7 During the normal operation of. the pan.- t0graph,,the. lowering springs 31 are stressed to their fullextent by thev action of the fluid pressure in the cylinder 43. To retractthe pantograph. frame 6 to its lowered. position, it is merely necessary to: exhaust the fluid fromthe cylinder 43, thereby permitting the full tension: of the springs 31 to force the link 35 to the right and turn the crank arm 38 clockwise. V V

The fluid maybe exhausted from the cylinder at-a predetermined rate in order that the. piston rod 42 may be quickly forced. to the. right by the: springs 31. and the contact from the trolley conductor 20..-

It is desirable to quickly retract the contact member 16 to avoid drawing, a destructilve are between it and the trolley conductor 20. Further, in case. the trolley encounters members 16 be thereby rapidlydrawn. away a damaged portion of the conductor 20, the operator may quickly retract it to avoid entangling it with the damaged conductor.

During the retracting operation,- the springs 31 contract to such an extent that their tension is greatly reduced, as the pantograph frame 6 approaches its lowered position. a

Inasmuch as the upward biasing force of the springs 18 remains substantially con stant, due to the varying moment through the cam, the speed of the downwardly moving pantograph frame may be progressively reduced, and the frame 6 be thereby slowly brought to rest at its fully retracted position and without striking the supporting frame or other portions of the pantograph mcchanism a destructive blow.

It is, therefore, apparent that a panto-cgraph-trolley-operating mechanism embodymg the features of the invention may be utilized to extend a pantograph frame at a substantially constant relatively slow speed and engage a contact member with the trolley conductor steadily and without subjecting the latter to a destructive blow.

Further, the operating mechanism is adapted to maintain a constant pressure between the contact member and the trolley conductor and'to quickly adjust the contact member to any irregularities in that conductor. The lowering mechanism'that constitutes a part of this invention is adapted to quickly retract the contact member from the trolley conductor and lower it at a progressively decreasing speed, thereby bring mg it to rest in the fully retracted position without shock.

Although I have described and illustrated only one embodiment of my invention, it will-be obvious to those skilled in the art that various modifications may be made in the details of the construction and in the general arrangement of the various operating linkages without departing from the spirit and scope of the invention as defined in the appended claims.

I claim as my invention:

1. A pantograph-trolley structure comprising an extensible pantograph frame, a contact member carried by the frame and means for retracting the pantograph frame at a uniformly progressive decelerating speed.

2; A pantograph trolley comprising an extensible pantograph frame, means for extending and retracting the frame at predetermined speeds and means for uniformly reducing the retracting speed as the frame approaches its retracted position.

3. A pantograph trolley comprising an extensible pantograph frame, means for extending the frame at a predetermined sub stantially constant speed, and means for retracting the frame at a uniformly progres sive decreasing speed. r ;4.. In a pantograph trolley,::the combination with an extensible frame and a con- I tact member supported thereby of means for exerting a substantially constant upward pressure upon the contact member, means for. exerting auniformly progressive decreasing downward force upon the frame for retracting the contact member, means for counteracting the retracting force, and means for controlling the counteracting means to thereby regulate the position and movement of the trolley. I

5. In a pantograph trolley,-in combination, 30 an extensible pantograph frame, means for extending the frame at a predetermined speed, means for retracting the frame at a relatively great speed, and means for uniformly reducing the retracting speed during the movement of the frame.

6. In a pantograph trolley, in combination, an extensible pantograph frame, means for extending the frame at a predetermined speed, means for retracting the v frame at a relatively great speed, and means for uniformly reducing the retracting speed before the frame reaches its limiting position,

7. A pantograph-trolley structure comprising an extensible pantograph frame,

spring means connected to the frame for biasing it in the upward direction, said a spring means being disposed to exert a substantially constant force upon the frame in- 10( all positions, a second spring for biasing the frame in the downward direction, said second spring being disposed to exert its greatest force when the frame is at its highest I 7 the shafts, spring means connected to the lost-motion mechanism for retracting the trolley, and fluid-pressure means for opposing the spring means to permit the trolley to be extended under the influence of the 12 first-named resilient means only by virtue of the lost-motion mechanism.

Q varying degrees of unbalance, said lowering springs beingthestronger, and Controlled means for supplementing the force of the raising springs to faise th'e pantograph frame structure.

In testimony whereof, Ihave'hereunto subscribed my name thiswfourth day of November, 1927. Y I b JOHN A.'CLARKE, JR. 

